The preparation of satisfactory or even reasonably satisfactory pipe varnish compositions for steel pipe during storage under atmospheric or weather conditions or the like has presented numbers of problems. Even today, in large plants which produce steel pipe, varnish compositions which are commercially used are commonly characterized, when applied to the steel pipe, by the usual spraying or otherwise coating of presently used pipe varnish compositions, by sagging which results in an uneven film build. In illustrative instances, the application of the pipe varnish compositions produce a film thickness of as little as 0.5 mils at the top of the pipe while, at the bottom of the pipe, there is literal dripping, creating undesirable "housekeeping" problems. Moreover, due to the marginal corrosion protection properties of various presently used pipe varnish compositions and the inconsistent and nonuniform film build, high rejection rates after outdoor storage of the varnished or coated steel pipe are encountered, being not uncommonly in excess of 30% after 6 months of outdoor storage. Such deficiencies have caused the rejection of appreciable amounts of steel pipe after outdoor storage with consequent substantial economic loss.
Traditional pipe varnishes comprise or consist of low cost quick drying alkyd resins cut back to about 50% solids with volatile organic solvents. Due to better solvency and a relatively fast evaporation rate a solvent such as xylene is commonly used. This choice of such solvents creates an extreme fire hazard in plant operations as the flash point is generally in the range of 70.degree.-85.degree. F. Such traditional pipe varnish compositions commonly have marginal corrosion resistance. They give only 100-200 hours salt fog protection at 1 mil dry film. The relatively low solids content and lack of any thixotropic character give traditional pipe varnish compositions bad film build and application characteristics. When spray applied to a hopefully consistent 2 mils film thickness, such pipe varnish compositions, as noted above, display very bad film sag (running) on curved surfaces. This results in low film thickness, as stated above, on the top of the pipe and an over-build and dripping of the pipe varnish composition on the bottom of the pipe.
Many efforts have been made over a substantial period of time to solve the problems and to attempt to arrive at suitable, or at least reasonably suitable, pipe varnish compositions. Certain of such efforts have involved the utilization in admixture with hydrocarbon resins such as ESCOREZ (Exxon Company) and with known volatile organic solvent-based wax-modified rust or corrosion-inhibiting compositions (hereafter referred to as "corrosion-inhibiting compositions") of the type of inorganic-organic complexes in the form of thixotropic overbased calcium organic calcium sulfonates complexed with calcium carbonate, and in certain cases in conjunction with one or more additional ingredients, particularly more than one, selected from the group of petrolatums; oxidized petrolatums; waxes such as slack wax, and crude or refined microcrystalline waxes (non-oxidized or oxidized); various resins; and the like. The thixotropic overbased calcium organic sulfonates sought to be so utilized are, per se, well known to the art as corrosion-inhibiting coating compositions, one well known group being sold under the registered trademark "SACI" (Witco Chemical Corporation, New York, N.Y.), being advantageously derived from alkyl benzene sulfonic acids in which alkyl contains from 12 to 30 carbon atoms. These thixotropic overbased organic sulfonates comprise, most advantageously, complexes of calcium organic sulfonates with crystalline calcium carbonate in colloidal or extremely finely divided form. While the use of such proposed pipe varnish compositions brings about certain improvements in relation to producing films having appreciably reduced sagging problems and in various other respects, other deficiencies, such as, for instance, the extent of resistance to deterioration in relation to ultraviolet light (U.V.) and inadequacy of film hardness, and also cost factors, has resulted in a failure commercially satisfactorily to meet the problems.